Quantum decoherence of nanodevices under convective and radiative boundary conditions

Abstract

Low dimensional nanostructures under thermal transport conditions have been traditionally treated as closed quantum systems. Many emerging operational nanodevices, however, will interact with their environment through convection and radiation processes. The realistic treatment of boundary conditions apart from internal conduction must now be quantified. Starting with a nanostructure operating in the ballistic or quasiballistic transport regime, the behavior of coherent carrier transport is investigated with the onset of convection and radiation interactions. Quantum decoherence is found to occur due to nanostructure heat carrier correlations to the fluid molecules or photons. Diagonalization of the quantum density matrix follows and serves as a mechanism to induce classicality on the heat carrier transport regime. Numerical experimentation has been performed with a silicon nanowire modeled under convective and radiative boundary conditions. Decoherence time scales of the nanowire are characterized for varying gaseous flow speeds, temperatures, and radiation environments. The magnitude of environmental coupling is also investigated to determine the decoherence behavior. Decoherence time scales are found to range from 300nsto7ms with gaseous convection producing the shortest temporal evolution. The loss of coherence has been found in every case analyzed, thus suggesting the transport regime to lie in classical phase space for this type of open quantum system. The transformation of heat carrier coherent quantum transport to the classical structure of phase space with the onset of environmental thermal interactions such as gas/liquid molecules or photons represents the major result of this work. The predictable outcome of preferred pointer states is discussed with the possibility of fabricating nanostructures that exhibit predetermined engineered thermal transport behavior under a specific set of boundary conditions.